1. Field of the Invention
This invention relates to an electric motor driven motorcar, and, more particularly, to an improved starting apparatus for a gas turbine-generator mounted on the electric motor driven motorcar.
2. Description of the Prior Art
Several attempts have been made to render clean the waste gas from a motorcar. One of these attempts has been to use a battery device for energization of an electric motorcar. However, as is well known in the battery motorcar art, it has been difficult to achieve long distance driving without battery exchange. The battery car also has the defect that the battery life is shortened when a variable load current is repeatedly drained from the battery because a variable torque loads the electric motor during the running of the car.
There has recently been developed and put to practical use an electric motor driven car having a hybrid driving system which consists of a floating battery device and an engine-generator for charging the battery by the output of the car. In accordance with this hybrid driving system, it is possible to run the internal combustion engine with a relatively constant rotational speed in spite of the load variation on the electric driving motor so that the waste gas from the engine involves few substances which pollute the air.
For this purpose, a Diesel engine has preferably been employed for driving the A.C. motor. However, as is well known, the Diesel engine has the significant defect that is quite heavy in weight/HP so as not to be suited for use with an electric motor driven motorcar.
From the above point of view, a small size gas turbine which has a rated output of 50 to 100 PS and which is capable of running with a high rated rotational speed of several million r.p.m. has been developed for driving the generator by the gas turbine mounted on the electric motor driven motorcar.
However, with a high speed gas turbine, the specific problem has been found that the gas turbine must raise its rotational speed from zero to at least 30% of the rated speed to enable self ignition upon the starting of the gas turbine. However, if the compressed air compressed by the rotary compressor of the gas turbine and supplied to the combustion chamber thereof is not at a predetermined pressure due to a low running speed of the gas turbine, the mixed gas will not be at a temperature capable of self ignition in the combustion chamber.
It has further been found that cell motors which are available in the general market at present are not capable of driving the gas turbine at a high speed of 60,000 of 80,000 r.p. m. without the help of specifically designed transmission gear. However, such transmission gear with over-drive is too expensive and complicated to manufacture to be practical.